linux-kernel - watchdog: sp5100_tco support for AMD V/R/E series

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Message-ID: <15c8913e-9026-2649-9911-71d6f1c79519@siemens.com>
Date:   Mon, 7 Sep 2020 13:20:58 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Guenter Roeck <linux@...ck-us.net>, linux-watchdog@...r.kernel.org
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-kernel@...r.kernel.org,
        "Awan, Arsalan" <Arsalan_Awan@...tor.com>,
        "Hombourger, Cedric" <Cedric_Hombourger@...tor.com>,
        "Farnsworth, Wade" <wade_farnsworth@...tor.com>
Subject: watchdog: sp5100_tco support for AMD V/R/E series

Hi all,

Arsalan reported that the upstream driver for sp5100_tco does not work
for embedded Ryzen. Meanwhile, I was able to confirm that on an R1505G:

[   11.607251] sp5100_tco: SP5100/SB800 TCO WatchDog Timer Driver
[   11.607337] sp5100-tco sp5100-tco: Using 0xfed80b00 for watchdog MMIO address
[   11.607344] sp5100-tco sp5100-tco: Watchdog hardware is disabled

..and fix it:

diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
index 85e9664318c9..5482154fde42 100644
--- a/drivers/watchdog/sp5100_tco.c
+++ b/drivers/watchdog/sp5100_tco.c
@@ -193,7 +193,8 @@ static void tco_timer_enable(struct sp5100_tco *tco)
 		/* Set the Watchdog timer resolution to 1 sec and enable */
 		sp5100_tco_update_pm_reg8(EFCH_PM_DECODEEN3,
 					  ~EFCH_PM_WATCHDOG_DISABLE,
-					  EFCH_PM_DECODEEN_SECOND_RES);
+					  EFCH_PM_DECODEEN_SECOND_RES |
+					  EFCH_PM_DECODEEN_WDT_TMREN);
 		break;
 	}
 }

Does anyone have an idea if such unconditional setting could be 
problematic on older/different efch? We probe for that bit in
sp5100_tco_setupdevice but we never set it so far.

I'm missing specs...

Thanks,
Jan

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